When we bought our ASX we went for the 2WD 1.8 DiD Diesel as it was much more responsive than the petrol. While it did cost more we felt that due to its improved fuel efficiency over the petrol variant it would be worth it. The official stats for the car are as follows
|Urban mode||6.7 (42.2)|
|Extra urban mode||4.8 (58.9)|
|Combined mode||5.9 (47.9)|
When we first got the car one of the first journeys we did was from Southampton to Wetherby. A nice trip of around 260 miles. Before the journey we filled the tank and then had the trip computer set to “Auto” (which means it gives a rolling average of the last 50km) and through the whole journey the computer was saying > 60mpg. Most of the journey was done between 60-70mph with mostly constant speed.
We made a couple of other short journeys and then filled up the tank… the result – 38,6mpg – Yes thats LESS then quoted Urban value for what is definitely Extra Urban driving. I was expecting it to be AT LEAST into the 50mpg range.
After a few more fill-ups of equally poor numbers compared to the trip computer ( Real mpg values of 33.1, 40.0, 38.7, 37.2)
This got me thinking to how accurate the trip computer was. After lots of research there was no easy way to get it to give a readout for a “trip”. It would always reset it self every day to 0! After a bit of research I found that you could get the car ECU to not reset from Manual Mode to Auto so this change was made and the car had what most people expect a trip computer to do
This resulted in some very interesting numbers clearly showing that Mitsubishi are not playing ball with the trip computer. Its amazing to see how in-accurate it is considering its one of the simplest things to work out. You only need 2 things. Distance traveled (it knows this from the milometer) and how much petrol its used (it knows how much its injecting).
So far I have done 4.5 full tanks
|Distance||Trip MPG||MPG||L/100km||Trip Accuracy|
The first 2 tanks included around 220-250 miles of motorway driving =~ half the tank so I would have expected to achieve a rate somewhere around the combined rate = 47.9
So from those numbers we can see that the trip computer was OVER READING by 41.2%, 51.0% and 40.9%
You could ‘maybe’ understand it being 5%? out but those numbers are just silly. My previous car was always within 0.5mpg of the real rate and our Mazda 3 is within 1mpg of the real rate.
Are Mitsubishi trying to pull a fast one – trying to con the media when they test their cars. How many do a real fuel consumption test and how many just rely on the published and trip computer numbers.
Once I have a few more readings I will see what Mitsubishi have to say.